Friction false-twist device

ABSTRACT

A friction false-twist device has at least one pair of friction discs mounted on parallel shafts for rotation about the axes thereof and a swivel shaft has at least two thread-guide elements thereon arranged so that at least one guide element is above and one guide element is below the discs.

United States Patent 1191 Raschle [4 Aug. 13, 1974 FRICTION FALSE-TWISTDEVICE 3,495,391 2/1970 Njo 57/77.42 inventor: Josef Raschle,Buetschwil, 3,668,853 6/1972 Lang 57/77.4 X

Switzerland [73] Assignee: l-leberlein & C0. AG, Wattwil, PrimaryExaminer-John Petrakes Canton of St. Gallen, Switzerland Attorney,Agent, or FirmFitzpatrick, Cella, Harper 22 Filed: May 1, 1973 5cm) [21]Appl. No.: 356,206

[30] Foreign Application Priority Data [57] ABSTRACT May 3, 1972Switzerland 6588/72 1 A fr1ct1on false-twlst devlce has at least onepair of 52 US. (:1. 57/106, 57/77.4 friction dim mounted on ParallelShafts for rotation 51 Int. Cl. D0lh 13/04, D02g 1/08 about the axesthereof and a Swivel Shaft has at least 58 Field of Search57/77.3-77.45, two threadeuide elements thereon arranged so that at57/10 least one guide element is above and one guide ele- I ment isbelow the discs. 7 [56] References Cited UNITED STATES PATENTS 13Claims, 10 Drawing Figures 2,227,910 1/1941 Pool 57/77.4 X 1 FRICTIONFALSE-TWIST DEVICE This invention relates to false-twist devices, andmore particularly to such devices utilizing friction elements consistingof a pair of rotatable discs between which the yarn to be twistedadvances, and wherein a threadguide device controls the position of theyarn prior to entry between the discs and subsequent to leaving same.

Devices for the production of false-twist in textile yarns are known inwhich the twist is imparted to the yarn by direct frictional contactwith rotating surfaces. Thus, for example, a device is disclosed inGerman patent specification No. 253,786 in which the yarn to be twistedis passed, in axial or nearly axial direction, through the arc throatbetween two rollers rotating in the same direction and with the samecircumferential speed. The rollers are provided with ribs and groovesand arranged so that the ribs of one roller engage with the grooves ofthe other roller. This measure is taken to prevent the yarn from movingout of the engagement position. Experiments have proved however that,with such apparatus, the path of the yarn is entirely out of control andthat, therefore, uniform yarn engagement and required uniform yarnquality cannot be obtained.

Furthermore, a similar device is disclosed in- Swiss patentspecification No. 341,103 in which the yarn is passed in frictionalcontact with a number of circular discs arranged on parallel shafts bymeans of threadguides provided above and below the-discs to provide ayarn path parallel with the disc shafts. According to a firstembodiment, the circular discs of the two shafts may have a distancebetween each other corresponding approximately to the yarn thickness,the yarn being maintained on the straight line between the two discshafts by means of the thread-guides. Because of the irregular diameterof the textile yarns to be treated, of play of the disc shafts and therelatively rapid wear of the disc rims, uniform yarn entrainment is notassured. Also with this device, it is not possible to obtain uniformyarn quality.

According to another embodiment of the known device. subsequent circulardiscs can mutually overlap and the yarn is maintained between theoverlapping portions of the discs by means of the thread-guides.Experiments have also shown that this solution does not providesufficient pressing of the yarn against the disc rims to assure safeuniform yarn engagement so that, again, the required uniform yarnquality cannot be obtained.

Accordingly, I have conceived by the present invention a false twistdevice whereby I am able to avoid the disadvantages of the knowndevices. Thus, in essence the present invention relates to a frictionfalse-twist device for textile yarns with at least one friction elementconsisting of at least one pair of discs characterized in that athread-guide arrangement is provided which consists of at least twothread-guide elements arranged to swivel on a common shaft so that, inoperating position, there is a thread-guide element at least above andbelow each friction member.

The friction member may advantageously consist of two axially parallelcircular discs the rims of which overlap in a zone of between I and mm.,preferably between 3 and 4 mm. or the rims of which are provided withmutually engaging profiles, the thread-guide elements being so arrangedon the swivelling shaft that they are intercepted by an imaginarystraight line extending between the disc shafts when the unit is inoperation, i.e. a line perpendicular to the axes of the shafts. Thethread-guide elements may be situated in the middle of the straight linebetween the disc shafts or by symmetrically displaced with respect tothis central point. The thread-guide elements may consist of low-wearmaterial, for example a hard metal such as wolfram carbide, may be ofannular or tubular shape, and may have maximum interior widths ofbetween 0.5 and 3mm. They may also be formed with a yarn introductionslot which may, for example, be of V, U or L shape and may abut againsta stop when being swivelled into readiness for operation. Thisembodiment of the thread-guide elements permits yarn introduction whilethe machine is in operation. The thread-guide elements, or moreprecisely, their ends lying opposite the friction discs, may be spacedfrom each other by a distance of up to 30mm;

There has thus been outlined rather broadly the more important featuresof the invention in order that the detailed description thereof thatfollows may be better understood and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterand which will form the subject of the claims appendedhereto. Thoseskilled in the art will appreciate that the conception upon which thisdisclosure is based may readily be utilized as a basis for the designingof other structures for carrying out the several purposes of theinvention. It is important, therefore, that the claims be regarded asincluding such equivalent constructions as do not depart from the spiritand scope of the invention.

Specific embodiments of the invention have been chosen for purposes ofillustration and description, and are shown in the accompanyingdrawings, forming a part of the specification wherein:

FIG. 1 is a top plan view of a first embodiment of the presentinvention;

FIG. 2 is a front elevational view of the device of FIG.

FIG. 3 is a detail of FIG. 1 on an enlarged scale;

FIGS. 4a, 4b are cross-sectional views taken along lines A-A and B-B,respectively, of FIG. 3;

FIG. 5 is a top plan view of a second embodiment of the invention;

FIG. 6is a front elevational view of the device of FIG.

FIG. 7 is a plan view of an embodiment with a device for controlling thethread-guides according to yarn tension;

FIG. 8 is a side elevation of the device of FIG. 7 in the direction ofarrow C; and

FIG. 9 is a further embodiment of the invention shown in frontelevation.

The device of FIGS. 1 and 2 includes two circular discs 1 and 2 formedof an elastomeric material, such as polyurethane, the rims of whichmutually overlap by approximately between 3 and 4 mm. The discs 1, 2 areplaced onaxially parallel shafts 3, 4 which are driven in the samedirection and with the same revolution speed by suitable drive means(not shown). Depending on yarn thickness, the distance between the discsis from 0.5 to 1.5 mm. I also provide a shaft 5 rotatable about its axiswhich is parallel to the axes of the shafts 3 and 4 and on this shaft Imount carrier rods 6, 7 extending transversely with respect to the shaft5, and on the free ends of which I mount the tubular thread-guideelements 8, 9 consisting of hard metal, such as Wolfram carbide. Thecarrier rods 6, 7 with the thread-guide elements 8, 9 can be swivelledsimultaneously in the direction of the arrow A from the operatingposition shown in solid lines to the phantom line position by rotatingshaft 5. In the operating position, the thread-guide elements 8, 9 arecentered along a straight line between the axes of shafts 3, 4 and arefixed in the operating position by means of a detent latching device 22.The yarn 20 then runs along the path shown in FIG. 2, the tangentialyarn engagement forces from the rims of the two discs 1, 2 beingdirected oppositely.

FIGS. 3, 4a and 4b show the overlapping rims of discs 1, 2 and twodifferent positions of the thread-guide elements 8, 9 on an enlargedscale. If the thread-guide elements are exactly on the straight line AAof the axes (not shown) of shafts 3, 4, the yarn 20 passes over the rimsof discs 1, 2 with maximum wrap angles 01,, a, (FIG. 4a). The furtheraway the thread-guide elements 8, 9 are from line A-A, the smaller arethe wrap angles a,, a as can be seen from FIG. 4b. It is thereforeimportant that the thread-guide elements, when in operation, should beon or as close as possible to the line AA to assure optimal yarnengagement.

The device of FIGS. 5, 6 differs from that of FIGS. 1, 2 in that thethread-guide elements 10, 11 are symmetrically displaced with respect tothe center of the straight line between the axes of the shafts of thediscs and in that these elements are U-shaped and are pressed againstthe stop 13 by means of spiral spring 12 and are thus fixed in thecorrect position for operation. The displaced arrangement ofthread-guide elements 10, 1] permits very exact control of yarn movementon the friction surfaces of discs 1, 2 since, as can be seen from FIG.6, the yarn 20 runs from thread-guide element to the rim face of disc 1along a straight line and runs from the rim surface of disc 2 to thethreadguide element 11 also in a straight line.

The device of FIGS. 7, 8 also shows two circular discs 1, 2 withoverlapping rims. On the carrier rod 6 is fixed a flexible cord or cable14 which runs over guide roller 15 and on the other end carries a weight16. With this device, which may for example also be replaced by atraction spring, it is possible to control the guiding of the yarnsdepending on variations of yarn tension so that the yarn guide elementsare always on or as near as possible to the straight line between theaxes of the discs.

In the device of FIG. 9, two discs 19, 21 are provided in the same planeon parallel shaft l7, 18, the rims of which have mating step-shapedprofiles which engage with each other. The thread-guide device is thesame as shown in FIGS. 1, 2. v

The advantages obtainable by the device of the present invention lieparticularly in the fact that exact control of yarn movement on thefriction surfaces is possible by precisely guiding the yarns at theinput and output ends of the friction elements. It furthermore assuresuniform yarn engagement and therefore very uniform yarn quality. Safeyarn engagement because of he maximum wrap angles of the yarns on thedisc rims furthermore permits the use of friction surfaces of morewearresistance, but with lower friction coefficients than elastomericmaterials, such as for example metal oxide ceramic material. Theengageable and disengageable thread-guide device furthermore permits meto bring the yarn into frictional contact with rotating friction elements or to remove the yarn from the latter.

I believe that the construction and operation of my novel frictionfalse-twist device will now be understood and that the severaladvantages thereof will be fully appreciated by those persons skilled inthe art.

I claim:

1. Friction false-twist device for textile yarns with at least onefriction element consisting of a pair of parallel shafts and at leastone disc mounted for rotation about the axis of each shaft thereof,characterized by a swivel shaft (5) and a thread-guide device whichcomprises at least two thread-guide elements (8, 9) adapted to guide ayarn end serially traversing the elements and so arranged on said shaftthat in operation at least one thread-guide element is present above andone below the respective friction elements, whereby a yarn end maytraverse one guide element before and the other guide element afterrunning over the friction element.

2. Device according to claim 1, wherein said discs overlap in a zone ofbetween 1 and 10 mm.

3. Device according to claim 2, wherein said discs overlap in a zone ofbetween 3 and 4 mm.

4. Device according to claim 2, wherein the distance between said discsat the overlapping zones thereof is between 0.5 and 1.5 mm.

5. Device according to claim 1, wherein said friction element comprisestwo axially parallel circular discs, characterized in that thethread-guide elements (8, 9; 10, 11) are so arranged on said shaft (5)that they each extend perpendicular to each of the discs shafts when inoperation.

6. Device according to claim 5, characterized in that the thread-guideelements (8, 9) are centrally positioned along a straight line betweenthe disc shafts when in operation.

7. Device according to claim 5, characterized in that the thread-guideelements (l0, 11) are in a symmetrically displaced position from themiddle of a line perpendicular to the axes of said disc shafts when inoperation.

8. Device according to claim 5, characterized in that means (12, 13, 22)are provided maintaining the posi tion of said thread-guide elements inoperation.

9. Device according to claim 5, characterized in that means (l4, l5, 16)are provided to control the position of the-thread-guide elements whenin operation responsive to the tension in the yarn.

10. Device according to claim 1, characterized in that the thread-guideelements (8, 9) are of tubular shape.

11. Device according to claim 10, characterized in that the thread-guideelements have an interior width of between 0.5 and 3mm.

12. Device according to claim 1, 1, characterized in that thethread-guide elements have a slot through which the yarn may beinserted.

13. Device according to claim 1, characterized in that the respectiveextremities of said thread-guide elements be opposite the circular discsand are spaced a distance from each other of up to 30 mm.

UNITED sTATEs PATENT OFFICE CERTIFICATE OF CORRECTION Dated August 13,1974] Patent No. 3 828,541

InVentOr(s) JOSEF RASCHLE It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Co1umn 4',' line 59, change "l,l," to l,

Signed ahd sealed this lQth day oi December 197A.

(SEAL) Attest:

MCCOY M. GIBSON- JR. c. MARSHALL DANN Attesting Officer Commissioner ofPatents FORM PO-1050 (10-69)

1. Friction false-twist device for textile yarns with at least onefriction element consisting of a pair of parallel shafts and at leastone disc mounted for rotation about the axis of each shaft thereof,characterized by a swivel shaft (5) and a threadguide device whichcomprises at least two thread-guide elements (8, 9) adapted to guide ayarn end seriallY traversing the elements and so arranged on said shaftthat in operation at least one thread-guide element is present above andone below the respective friction elements, whereby a yarn end maytraverse one guide element before and the other guide element afterrunning over the friction element.
 2. Device according to claim 1,wherein said discs overlap in a zone of between 1 and 10 mm.
 3. Deviceaccording to claim 2, wherein said discs overlap in a zone of between 3and 4 mm.
 4. Device according to claim 2, wherein the distance betweensaid discs at the overlapping zones thereof is between 0.5 and 1.5 mm.5. Device according to claim 1, wherein said friction element comprisestwo axially parallel circular discs, characterized in that thethread-guide elements (8, 9; 10, 11) are so arranged on said shaft (5)that they each extend perpendicular to each of the discs shafts when inoperation.
 6. Device according to claim 5, characterized in that thethread-guide elements (8, 9) are centrally positioned along a straightline between the disc shafts when in operation.
 7. Device according toclaim 5, characterized in that the thread-guide elements (10, 11) are ina symmetrically displaced position from the middle of a lineperpendicular to the axes of said disc shafts when in operation. 8.Device according to claim 5, characterized in that means (12, 13, 22)are provided maintaining the position of said thread-guide elements inoperation.
 9. Device according to claim 5, characterized in that means(14, 15, 16) are provided to control the position of the thread-guideelements when in operation responsive to the tension in the yarn. 10.Device according to claim 1, characterized in that the thread-guideelements (8, 9) are of tubular shape.
 11. Device according to claim 10,characterized in that the thread-guide elements have an interior widthof between 0.5 and 3mm.
 12. Device according to claim 1, 1,characterized in that the thread-guide elements have a slot throughwhich the yarn may be inserted.
 13. Device according to claim 1,characterized in that the respective extremities of said thread-guideelements be opposite the circular discs and are spaced a distance fromeach other of up to 30 mm.